问题
解答题
在10件产品中,有3件一等品,4件二等品,3件三等品,从这10件产品中任取3件,求取出的3件产品中一等品件数X的分布列。
答案
解:由于从10件产品中任取3件的结果数为,
从10件产品中任取3件其中恰有k件一等品的结果数为,
那么从10件产品中任取3件,
其中恰有k件一等品的概率为P(X=k)=,k=0,1,2,3,
所以随机变量X的分布列是
。
在10件产品中,有3件一等品,4件二等品,3件三等品,从这10件产品中任取3件,求取出的3件产品中一等品件数X的分布列。
解:由于从10件产品中任取3件的结果数为,
从10件产品中任取3件其中恰有k件一等品的结果数为,
那么从10件产品中任取3件,
其中恰有k件一等品的概率为P(X=k)=,k=0,1,2,3,
所以随机变量X的分布列是
。
通读下面短文,掌握其大意,然后在各题所给的A、B、C三个选项中,选出一个最佳选项。 A young man was going to spend his holiday in a mountain village. That night he 1 at a small hotel (旅馆) near the train station. 2 going to bed, he went to the owner of the hotel and said, " Excuse me, sir. Will you please 3 me up at four forty-five tomorrow morning? I'll take the five o'clock 4 ." "Oh, sorry," the owner said in ![]() The young ![]() ![]() clock (闹钟)? Maybe it can help me." "Yes, here you a ![]() The young man thanked the owner 7 . But as he looked at the ![]() ![]() was 8 wrong with it. "Will it 9 on time? " he asked. "Sure! You just give it a good shake ( 摇晃 ) at a quarter 10 five, and it will do! " | ||||
|